A characteristic determining device is provided which determines fuel injection characteristics of a plurality of fuel injectors for an internal combustion engine. The characteristic determining device includes a pressure sensor and a plurality of pipes each of which connects between the pressure sensor and one of the fuel injectors. The pressure sensor is designed to have a plurality of pressure inputs from the respective fuel injectors through the pipes and outputs a signal indicative of a level of pressure in each of the fuel injectors. The characteristic determining device analyzes the signals from the first pressure sensor to determine the fuel injection characteristics of the respective fuel injectors. These arrangements result in a simplified structure of the characteristic determining device and a decreased manufacturing cost thereof.

Methods and systems are provided for a fuel injector diagnostic. In one example, a method may include modifying an injection pattern to determine a relative fuel mass error of an injector. A fuel injector correction may be determined based the relative fuel mass error.

Methods and systems are provided for balancing a plurality of fuel injectors. In one example, a method includes adjusting port-fuel injecting parameters in response to a learned direct injector fueling error.

An engine system incorporating an engine, one or more sensors, and a controller. The controller may be connected to the one or more sensors and the engine. The one or more sensors may be configured to sense one or more parameters related to operation of the engine. The controller may incorporate an air-path state estimator configured to estimate one or more air-path state parameters in the engine based on values of one or more parameters sensed by the sensors. The controller may have an on-line and an off-line portion, where the on-line portion may incorporate the air-path state estimator and the off-line portion may configure and/or calibrate a model for the air-path state estimator.

Disclosed is a method for controlling an engine torque for a diesel engine, characterized in that the engine torque control is implemented in an injection system. The injection system in question includes a high-pressure pump controlled by an engine control unit, the high-pressure pump supplying a fuel supply rail, the pump being dimensioned to be capable of delivering a capacity volume of compressible fuel for each combustion cycle of the diesel engine. It also includes a pressure sensor for measuring the pressure of the fuel in the fuel rail.

An engine system including a fuel system control arrangement includes an internal combustion engine including an exhaust line, one or more cylinders, and one or more fuel injectors corresponding to the one or more cylinders, means for determining fresh air mass flow into an intake to the engine, a nitrogen oxide (NOx) sensor in the exhaust line, and a controller configured to determine oxygen (O2) in exhaust gas based on a signal from the NOx sensor and to calculate a current fuel injection quantity based on the O2 in the exhaust gas and determined fresh air mass flow into the intake, to compare the current fuel injection quantity to a theoretical fuel injection quantity under current operating conditions, and to adjust an amount of fuel injection from the one or more fuel injectors when the current fuel injection quantity differs from the theoretical fuel injection quantity to make the current fuel injection quantity closer to the theoretical fuel injection quantity.

An engine control device includes a model that, based on engine operating condition and first-type operation amount, reproduces at least one index from among various indexes of combustion state of engine, and a processor that executes a process including deciding on second-type operation amount, by optimization using the model so as to treat at least one of the indexes, which are reproduced by the model, as estimated value of control amount, and ensure that the estimated value of the control amount follows control target value, associating the second-type operation amount with the control target value and the engine operating condition, rewriting a learning control table in which operation amount corresponding to the control target value and the engine operating condition is registered, and calculating operation amount according to the learning control table based on the control target value and the engine operating condition.

A method and a device for ascertaining a fluid injection quantity of an injection system. The injection system includes a high-pressure pump, a high-pressure region that adjoins the high-pressure pump, a pressure sensor, and an injector that is fed from the high-pressure region. The method includes detecting a measurement signal using the pressure sensor and segmenting a first pressure profile from the measurement signal. The first pressure profile characterizes the pressure profile prior to a fluid injection using the injector. The method also includes segmenting a second pressure profile from the measurement signal. The second pressure profile characterizes the pressure profile after the fluid injection using the injector. The method also includes performing a core density estimation using the first pressure profile and the second pressure profile, ascertaining a pressure difference, and ascertaining the fluid injection quantity using the pressure difference.

A microcomputer determines that an abnormality has occurred in calculation functions regarding calculation of an injection amount command value and the like, based on a deviation of the injection amount command value, in an increasing manner, from a monitoring injection amount. The microcomputer calculates, based on a cooling fluid temperature of an engine, a start-up injection amount such that the start-up injection amount becomes smaller when the cooling fluid temperature is high than when the cooling fluid temperature is low, and uses the start-up injection amount as the injection amount command value immediately after the completion of start-up of the engine. Besides, the microcomputer uses the smaller one of a start-up injection amount calculated this time and a monitoring start-up injection amount calculated last time, as a monitoring start-up injection amount that is used as the aforementioned monitoring injection amount immediately after the completion of start-up of the engine.

An ECU has a fuel pressure sensor that detects fuel pressure inside of a common rail. The ECU detects the fuel pressure at a predetermined frequency and calculates a drop amount of the fuel pressure in accordance with fuel injection by fuel injectors based on the detected fuel pressure. The ECU acquires a fluctuation amount of a fuel injection amount of each of the fuel injectors based on the drop amount of the fuel pressure and learns an injection characteristic of each of the fuel injectors, the injection characteristic indicating a correlation between the fuel injection amount and the fluctuation amount of the fuel injection. In a case in which a detection timing of the fuel pressure is within a fuel injection period of a predetermined fuel injector, the ECU disallows the learning of the injection characteristic using the fuel pressure detected in the fuel injection period.